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The spatial and temporal variations of radon concentration and meteorological parameters were measured in and around the Kuvempu University campus, situated in the Western Ghats of Shankaraghatta forest environment is measured by active technique using Scintillation cell and the meteorological parameters measured using Automatic Weather System (AWS. The activity concentration of radium in soil is determined by Gamma-ray spectrometer with NaI (Tl) detector. The measured data of the present study shows that the built-up environment and forest ecosystem have enhanced the natural radiation level. The variation of atmospheric radon concentration is depends on meteorological parameters, geographical and geophysical parameters. The diurnal variation shows the maximum concentrations were noticed in the early morning and minimum during afternoon. The seasonal variation shows maximum concentration during winter season and minimum during the summer season. These variations were mainly depending on meteorological parameters. The correlation between the radon concentration and the meteorological are discussed and presented in this paper. The present study was aimed to establish a base-line data of Annual effective dose equivalent (AED). The diurnal, seasonal variations in different environmental conditions were discussed and presented in this paper. [ABSTRACT FROM AUTHOR]

The large-scale conversion of vegetated land to urban use leads to a significant reduction in evapotranspiration (ET) due to the lack of vegetation, which may aggravate urban dry island (UDI) effect. Analysis of diurnal and seasonal (e.g. growing season) variations in UDI can help us to better identify the role of ET in processes of UDI. We compared six-hourly weather observation data (1980–2017) from 140 paired urban-rural stations across a large climatic gradient in China to explore how near-surface atmospheric dryness changed both diurnally and seasonally, and its relationship with urbanization-associated ecohydrological processes. We showed that the difference in atmospheric dryness (i.e. UDI intensity) between urban and rural areas, as measured by specific humidity (Δ q < 0), is more pronounced during the daytime and growing seasons. The nighttime urban wet island (UWI, Δ q > 0) effect partially offset daily UDI effect, which has made the latter underestimated. Intensified nighttime urban heat island (UHI) reduced the diurnal temperature range (DTR) in cities and thus enhanced nighttime UWI effect from 2000 to 2010. However, after 2010, nighttime UWI effect weakened or disappeared, whereas nighttime UDI intensified in humid cities, resulting in a significant increase in daily UDI. Intensified UHI and UDI are often closely coupled (synchronous occurrence) through latent heat (LE) or ET processes, especially after 2010. Our results indicate that the conversion of vegetated lands to urban impervious surface, especially in humid regions, leads to the reduction in transportation during daytime and evaporation at night in urban cores, which alters the relationships between near-surface air temperature, atmospheric moisture, and ET. The present diurnal and seasonal variations in UDI were delineated in detail to explicate the patterns and interconnections of local urban climate and surface ecohydrological processes, which are critical for ecosystem services in urban landscape design.

In order to obtain a better perspective of the impacts of brownfields on the land–atmosphere exchange of mercury in urban areas, total gaseous mercury (TGM) was measured at two heights (1.8 m and 42.7 m) prior to 2011–2012 and after 2015–2016 for the remediation of a brownfield and installation of a parking lot adjacent to the Syracuse Center of Excellence in Syracuse, NY, USA. Prior to brownfield remediation, the annual average TGM concentrations were 1.6 ± 0.6 and 1.4 ± 0.4 ng⋅m−3 at the ground and upper heights, respectively. After brownfield remediation, the annual average TGM concentrations decreased by 32% and 22% at the ground and the upper height, respectively. Mercury soil flux measurements during summer after remediation showed net TGM deposition of 1.7 ng⋅m−2⋅day−1 suggesting that the site transitioned from a mercury source to a net mercury sink. Measurements from the Atmospheric Mercury Network (AMNet) indicate that there was no regional decrease in TGM concentrations during the study period. This study demonstrates that evasion from mercury-contaminated soil significantly increased local TGM concentrations, which was subsequently mitigated after soil restoration. Considering the large number of brownfields, they may be an important source of mercury emissions source to local urban ecosystems and warrant future study at additional locations. [ABSTRACT FROM AUTHOR]

Tropospheric pollutants including surface ozone (O 3 ), nitrogen dioxide (NO 2 ), carbon monoxide (CO) and meteorological parameters were measured at a traffic junction (78°2′ E and 27°11′ N) in Agra, India from January 2012 to December 2012. Temporal analysis of pollutants suggests that annual average mixing ratios of tropospheric pollutants were: O 3 — 22.97 ± 23.36 ppbV, NO 2 — 19.84 ± 16.71 ppbV and CO — 0.91 ± 0.86 ppmV, with seasonal variations of O 3 having maximum mixing ratio during summer season (32.41 ± 19.31 ppbV), whereas lowest was found in post-monsoon season (8.74 ± 3.8 ppbV). O 3 precursors: NO 2 and CO, showed inverse relationship with O 3 . Seasonal variation and high O 3 episodes during summer are associated with meteorological parameters such as high solar radiation, atmospheric temperature and transboundary transport. The interdependence of these variables showed a link between the daytime mixing ratios of O 3 with the nighttime level of NO 2 . The mixing ratios of CO and NO 2 showed tight correlations, which confirms the influence of vehicular emissions combined with other anthropogenic activities due to office/working hours, shallowing, and widening of boundary layer. FLEXTRA backward trajectories for the O 3 episode days clearly indicate the transport from the NW and W to S/SE and SW direction at Agra in different seasons. [ABSTRACT FROM AUTHOR]

Estudos sobre a composição e variação diurna do zooplâncton do estuário do Pina (PE) foram reali;r.ados, baseando-se em 200 litros de água superficial, coletada e filtrada em uma rede com malha de 69 11m de abertura, durante os períodos seco Uaneiro e fevereiro/91) e chuvoso Uunho e julho/91), em um ciclo diurno de 12 h. Paralelamente, foram coletados dados hidrolÓgicos. O zooplâncton esteve representado por 19 taxa, além do meroplâncton. Destacaram-se Favella ehrenbergi, Brachionus plicatilis, Copepoda nauplii e Oithona osvaldocnlzi (♀). Valores quantitativos mais altos foram registrados no peJíodo seco. O máximo registrado foi de 411.7490rg.m-3 e o mínimo 2.6230rg.m-3 .As correntes de marés foram as principais responsáveis pela variação espacial do zooplâncton. A diversidade específica foi baixa, evidenciando processos seletivos no estuário.Composieionand daily variation of zooplankton in the estuary of Pina (Brazil- PE) was studied based on 200L of water filtered at surface through a net mesh size of 69 Jlm, during the dry (January-February/91) and the rainy (June-July/91) seasons. The samplcs were collected with time interval of three hours, during a daylight period. Concurrent hydrological data were obtained. Nineteen taxon of zooplankton were registered, including meroplankton, of which the most abundant was Favella ehrenbergi, followed by Brachionus plicatilis, Copepoda nauplii and Oithona osvaldocnlzi (♀). Higher quantitatives values occured in the dry reason. The maximum registered was 411,7490rg.m-3 and the minimum 2,6230rg.m-3 . The tidal currents were the main factor influencing the zooplankton spacial variation. Specific diversity was low, highlighting selcctive processes in the Pina estuary.

Aims Although stem CO2 efflux is critical to ecosystem carbon and energy balance and its feedback to future climate change, little information is available on stem CO2 efflux and its responses to temperature, especially in subtropical China. This study aims to (i) evaluate the temporal and spatial variations of stem CO2 efflux of three species, including oak (Quercus acutissima Carr.), masson pine (Pinus massoniana Lamb.) and loblolly pine (Pinus taeda Linn.) in subtropical China and (ii) analyze the temperature sensitivity of stem CO2 efflux in the three species based on 2-year field measurements. Methods We measured stem CO2 efflux and stem temperature (at 3 cm depth) of the three species using the horizontally oriented soil chamber technique from September 2008 to August 2010. We also conducted a 24-h measurement to examine the diurnal variation of stem CO2 efflux in three consecutive days in April 2009. Important findings The temporal dynamics of stem CO2 efflux followed the change of the stem temperature in a 3-cm depth with a bell-shaped curve in the three species. Stem temperature explained 77–85% of the seasonal variations of stem CO2 efflux over the entire study period in the three species. The temperature sensitivity (Q10) of stem CO2 efflux was obviously different among the three species with higher Q10 value found in oak (2.24) and lower values in the coniferous species (1.76 and 1.63). Our results also showed that the Q10 values of stem CO2 efflux in all the three species were lower in the growing season than that in the non-growing season, indicating that the growth and maintenance respiration had different temperature responses. Moreover, we found that the temperature-normalized stem CO2 efflux (R10) changed greatly between the growing and non-growing seasons in oak and masson pine, but not in loblolly pine. Additionally, we also found that in the non-growing season, the principal factor responsible for the spatial variation of stem CO2 efflux among the 15 sampling trees was sapwood volume, whereas in the growing season, stem CO2 efflux was closely related to annual dry-matter production in the three subtropical species. [ABSTRACT FROM PUBLISHER]

Abstract: The Chapman scale height H T at F2 peak, which can be used to construct a topside electron density profile model, is deduced from ground-based ionograms. In this paper, H T values obtained from ionograms recorded at the low latitude station Hainan (19.4°N, 109.0°E), China is used to study its diurnal, seasonal, and solar activity dependence. The correlations between H T and the F2 peak parameters foF2 and hmF2, the best-fitted IRI-parameter B0, and the ionospheric slab thickness τ are also studied. Data used for the present study covered a 2-year time period from March 2002 to February 2004. The present study showed that: (1) Diurnal course of the H T has two peaks, with the main one occurring at daytime hours around noontime and the other occurring before sunrise. The pre-sunrise peak is most obvious for winter compared with that for summer and equinox. The minimum values of H T occur around midnight and sunrise hours. The time of occurrence of the sunrise minimum is earliest for summer and latest for winter. (2) H T shows a clear annual variation with largest daytime values occurring in summer and smallest values in winter. (3) H T shows strong solar activity dependence, with the daytime value of H T decreasing with decreasing solar activity. (4) H T is strongly correlated with the bottomside F2 layer thickness parameter B0 and the ionospheric slab thickness τ. The high correlation between H T and B0 parameter suggests the possibility to construct the topside electron density profile model based on the B0 parameter previously established for the International Reference Ionosphere. [Copyright &y& Elsevier]

Size distribution of fine atmospheric aerosol was measured at K-puszta, Hungary during summer and winter of 2000 and spring and autumn of 2001. The sampling was carried out by an electrical low pressure impactor which fractionated fine particles (d<1.7 μm) in eight size ranges. In this paper diurnal and seasonal variations of the concentration and size distribution of fine sulfate, total carbon (TC) and water soluble organic compounds (WSOC) are presented. The results indicate that the concentrations of sulfate, TC and WSOC are different in different seasons. Potential sources of these variations are briefly discussed. [Copyright &y& Elsevier]

Eucalyptus is widely planted in South China and has high economic and ecological values. However, the seasonal drought in southern China severely limits the productivity of Eucalyptus plantation. In this study, the dry-season irrigation was carried out after the conventional production and planting of Eucalyptus. The diurnal changes of photosynthetic characteristics of Eucalyptus plantations were measured in July, October 2017 and January, May 2018 to explore the diurnal and seasonal variations and their responses to both dry-season irrigation and environmental factors. The results showed that during the first-year growth of Eucalyptus urophylla × E. grandis plantation, (1) the diurnal changes of the trees under different treatments showed single-peak curves with the varied occurrence time of the highest photosynthetic characteristics in different months; the E. urophylla × E. grandis without dry-season irrigation (CK and F) had transpiration midday depression in January and that with the only dry-season irrigation (W) exhibited both photosynthetic and transpiration midday depression in May. (2) The trees of CK and F were subjected to mild drought stress in the dry season and their maximum photosynthetic and transpiration rate were lower than those of W and WF treatment respectively, but they had higher maximum WUE. The trees of W had significantly higher daily net CO 2 assimilation and daily water transpiration in dry season. (3) The diurnal changes of photosynthetic characteristics were mainly influenced by water vapor pressure deficit (VPD) at the corresponding time of the month. (4) In the short-term treatments, dry-season irrigation and fertilization significantly increased the biomass of E. urophylla × E. grandis. Dry-season irrigation alleviated the mild drought stress for gas exchange in the dry season and further promote the biomass of E. urophylla × E. grandis. This study provided an important practical exploration for improving the productivity of E. urophylla × E. grandis plantation in seasonal arid areas. • Most diurnal photosynthetic and respiration rate showed "single peak" curves. • Environmental factors affected diurnal and seasonal photosynthetic characteristics. • Dry-season irrigation alleviated the mild drought stress for the growth. • CK and F had transpiration midday depression in January. • W exhibited photosynthetic and transpiration midday depression in May. [ABSTRACT FROM AUTHOR]

Although urban aerosols have been extensively explored, the variation of aerosols across space and time in the city and its underlying mechanism have not been quantitatively understood. This study defined the phenomenon of higher aerosols concentrations in the urban areas than in the surrounding rural areas as "Urban Aerosol Pollution Island (UAPI)" and quantified UAPI intensity using the urban-rural difference of Particulate Matter (PM10) concentrations. We investigated the diurnal and seasonal variations of UAPI and its relationship with Urban Heat Island (UHI) in the metropolitan area of Berlin using the combination of a long-term (2010– 2017) observation network and the WRF-Chem model. Observation data showed that UAPI existed at most of time, with more than one-quarter of the days showing daily mean UAPI intensity of more than 5 μg/m3 and 10.6 μg/m3, respectively at background and traffic stations. The PM10 concentrations and UAPI intensity at background stations showed opposite diurnal variations, with higher PM10 concentrations at night, but larger UAPI intensity in the daytime. Seasonally, both PM10 concentrations and UAPI showed larger values in winter. The seasonal variation of UAPI intensity was closely related to the air temperature. The colder days in winter and hotter days with heat wave in summer showed larger UAPI intensity. The UAPI was negatively correlated to UHI in summer. The mitigation of UHI increased PM10 concentrations in urban areas by ~3%, leading to a stronger UAPI. This study can contribute to the accurate risk assessment of aerosol pollution and the design of mitigation strategies. • This study investigated the temporal variation of urban aerosol pollution island (UAPI) intensity using PM10 data from observation network and WRF-Chem. • PM10 concentrations was higher at night, but UAPI intensity was larger in the daytime. • Both colder days in winter and hotter days with heat wave in summer showed larger UAPI intensity. • UAPI was negatively correlated with urban heat island (UHI) in summer. • Mitigation of UHI strengthened UAPI by weakening turbulent mixing and decreasing urban boundary layer height. [ABSTRACT FROM AUTHOR]

• Numerical contributions of typical landscapes to sensible heat flux are quantified. • Changes in sensible heat flux during the diurnal and season are quantified. • Controversial results based on remote sensing data are partly resolved. • The difference in sensible heat flux of typical landscapes is the greatest at 2 pm. Cooling energy consumption in urban areas is affected significantly by the dynamics of urban heat flux. However, we still lack a clear understanding of the quantitative contribution rate and underlying mechanism of typical urban landscapes to urban heat dynamics, especially in seasonal and diurnal patterns. Here we used a thermal infrared camera and portable meteorological instruments to examine the sensible heat flux (SHF) changes of five typical urban landscapes in Beijing based on surface temperature and concurrent microclimate conditions. Diurnal and seasonal variations of SHF were quantified by comparing changes in forenoon and afternoon in different seasons. Results showed that (1) walls and roads act as heat-source, while forests and water act as heat-sink in all seasons; however, grassland served as heat-sink in summer and spring-autumn, but it becomes a heat-source in winter. (2) The seasonal variation of sensible heat flux of the wall is the greatest, followed by water, while that of trees is the smallest. Besides, the highest sensible heat flux and the maximum variation among typical urban landscapes occur between noon and 2:00 pm. (3) The numerical contribution rate of typical landscapes to sensible heat flux varies with daytime (forenoon and afternoon) and seasonal changes, and these ratios can be used as parameters to adjust the numerical models to obtain more reliable results in surface-energy-flux-related studies. The results of this study can provide a reference for explaining controversial findings based on remote-sensing data, and provide insights into revealing the sensible heat flux mechanism of typical urban landscapes and cooling energy conservation in cities. [ABSTRACT FROM AUTHOR]

This study used a self-developed a NDIR monitoring system to continuously monitor GHG emissions from a tidal constructed mangrove wetland at three typical habitats (mudflat, mangrove, and water surface) in four seasons. The NDIR monitoring system is able to explore the diurnal and seasonal variation of GHG emissions from the tidal constructed mangrove wetland and to estimate more precisely for the GHG emission based carbon budget of the wetland. The continuous monitoring technique is feasible and valuable for assessing the temporal variation of GHG uptake/emission to/from the wetland. Daytime CO 2 emissions were always lower than those at nighttime due to photosynthesis process, while an opposite trend was observed for CH 4 and N 2 O emissions. Seasonal variation of GHGs showed that the highest GHG emissions was observed in summer, and followed by fall, spring, and winter. For three typical habitats, mangrove emitted more amounts of GHGs than mudflat and water surface. • This study used a self-developed a NDIR monitoring system to continuously monitor GHG emissions from a tidal constructed mangrove wetland at three typical habitats in four seasons. • NDIR monitoring system is able to explore the diurnal and seasonal variation of GHG emissions from the tidal constructed mangrove wetland and to estimate more precisely for the GHG emission based carbon budget of the wetland. [ABSTRACT FROM AUTHOR]